Led with integrated constant current driver

ABSTRACT

An LED package containing integrated circuitry for matching a power source voltage to the LED operating voltage, LEDs containing such integrated circuitry, systems containing such packages, and methods for matching the source and operating voltages are described. The integrated circuitry typically contains a power converter and a constant current circuit. The LED package may also contain other active or passive components such as pin-outs for integrated or external components, a transformer and rectifier, or a rectifier circuit. External components can include control systems for regulating the LED current level or the properties of light emitted by the LED. Integrating the power supply and current control components into the LED can provide for fabrication of relatively small LEDs using fewer and less device-specific components.

This application is a continuation of, and claims the benefit of, U.S.patent application Ser. No. 11/879,665, filed on Jul. 17, 2007.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to semiconductor devices, and moreparticularly to light emitting devices and methods of fabricating lightemitting devices with integrated drive electronics.

2. Description of Related Art

Light emitting diodes and laser diodes are well known solid stateelectronic devices capable of generating light upon application of asufficient voltage. Light emitting diodes and laser diodes may begenerally referred to as light emitting devices (LEDs). Light emittingdevices generally include a p-n junction formed in an epitaxial (epi)layer such as gallium nitride (GaN) grown on a substrate such assapphire (Al₂O₃), silicon (Si), silicon carbide (SiC), gallium arsenide(GaAs) and the like. The wavelength distribution of the light generatedby the LED depends on the material from which the p-n junction isfabricated and the structure of the thin epitaxial layers that includethe active region of the device. Commercial high-efficiency LEDs aretypically fabricated from two classes of III-V semiconductor materials.Group-III nitride (III-N) based materials are used for the color rangefrom ultraviolet to blue-green, and Group-III arsenide-phosphide(III-AsP) for yellow to near-infrared.

There has been a great deal of recent interest in LEDs formed ofGroup-III nitride based material systems because of their uniquecombination of material characteristics including high breakdown fields,wide bandgaps (3.36 eV for gallium nitride (GaN) at room temperature),large conduction band offset, and high saturated electron driftvelocity. The doped and active layers are typically formed on asubstrate that can be made of different materials such as silicon (Si),silicon carbide (SiC), and sapphire (Al₂O₃). SiC wafers are oftenpreferred for these types of heterostructures because they have a muchcloser crystal lattice match to Group-III nitrides, which results inGroup III nitride films of higher quality. SiC also has a very highthermal conductivity so that the total output power of Group III nitridedevices on SiC is not limited by the thermal resistance of the wafer (asis the case with some devices formed on sapphire or Si). Also, theavailability of semi-insulating SiC wafers provides the capacity fordevice isolation and reduced parasitic capacitance that make commercialdevices possible.

LEDs, which are current-sinking devices, typically require aconstant-current, direct-current power supply for efficient and stableoperation (e.g. to provide and maintain output intensity and color).Constant-current power supplies capable of matching the voltage supplyof an electronic system to the required voltage of an LED can take manyforms, but they require circuits composed of active components (e.g.,transistors, oscillators, operational amplifiers) as well as linear andnon-linear passive components (e.g. diodes, thermistors, inductors,capacitors, resistors). For high efficiency, the input voltage should bematched as well as possible to the operating voltage of the LED(s).

The power sources typically available within electronic devices arevoltage sources such as batteries, fuel cells, or rectifying orswitching power supplies to provide DC voltage from an AC mains supply.The LED circuits typically consist of one or more transistors,oscillators, or amplifiers connected to inductors and capacitors toprovide the constant current. The power supply (source) and currentcontrol components in current LED technologies are physically separatedfrom the LED, and these technologies suffer from one or more of thefollowing disadvantages with respect to power sources and controlcomponents:

(a) the voltage of the source is not typically matched to the operatingvoltage of the LED;

(b) the operating voltage of the LEDs, even those originating from thesame manufacturer and of the same part type and lot, are not usuallymatched well enough to allow for voltage source operation;

(c) the realization of drive circuitry external to LEDs can beproblematic for potential LED users who may be unfamiliar with thedesign of constant-current circuits; and

(d) applications in which space is limited cannot allow for powersupplies external to the LED.

SUMMARY OF THE INVENTION

Briefly, and in general terms, the present invention is directed tointegrated circuitry for matching the voltage supply of an electronicsystem to the required operating voltage of an LED. The integrated LEDpackage can be fabricated to provide a relatively small container forthe electronic components with terminals to provide electrical and/oroptical access. The present invention thereby provides a means tomanipulate a source voltage in order to match it with the operatingvoltage of an LED and helps eliminate the need to have or design aseparate power supply or current control circuit for any particular typeof LED.

The invention can be used in a wide variety of situations requiringlighting, including without limitation general lighting luminaires,portable electronic devices, and personal lighting

In particular, the present invention integrates the power supply andcurrent control components of an LED into fewer components; anLED/active driver plus the required external passive components. Havingsome of the power supply circuitry integrated into the LED simplifiesthe use of LEDs with constant voltage power supplies. A potential LEDuser, for example, would not need to design or have a separate powersupply or current control circuit. Although passive components suitablefor the available input voltage and the required current drive of theLED must still be chosen for a particular device or device type, thisshould generally be easier than designing an entire power supplycircuit.

In one of several aspects, the invention relates to a light emittingdevice package in which at least one LED, at least one voltage levelconverter, and at least one constant current circuit are electricallyconnected and integrated into the package. In yet another aspect, thedevice further includes at least one electrical connector. In yetanother aspect, the connector provides electrical connection to at leastone power source. In a further aspect, the connector provides electricalconnection to at least one control system. In a yet further aspect, thecontrol system provides control over at least one LED current. Inanother aspect, the control system provides control over at least oneproperty of light emitted by the LED.

In another aspect, the invention relates to a packaged LED having atleast one integrated voltage level converter and at least one constantcurrent circuit which are integrated into, and electrically connectedto, the LED. In yet another aspect, the invention elates to a lightemitting system containing the packaged LED. In a further aspect, thelight emitting system contains at least one power source. In a yetfurther aspect, the light emitting system contains at least one controlsystem. In another aspect, the control system is connected to thepackaged LED and provides control over at least one property of lightemitted by the LED.

In a further aspect, the invention relates to an LED containing at leastone voltage level converter and at least one constant current circuitthat are integrated into, and electrically connected to, the LED.

In another aspect, the invention relates to a method for matching apower source voltage to an LED operating voltage by providing a voltagelevel from a power source to drive circuitry which is integrated intothe LED, electrically connected to the LED, and provides a voltage levelto the LED. In a further aspect, the voltage level provided by thecircuitry is similar to or less than the voltage level provided by thepower source. In a yet further aspect, the voltage level provided by thecircuitry matches the operating voltage of the LED.

These and other aspects and advantages of the invention will becomeapparent from the following detailed description and the accompanyingdrawings which illustrate by way of example the features of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an integrated power supply LED according tothe present invention.

FIG. 2A is a schematic cross section view of one embodiment of aintegrated driver LED package according to the present invention.

FIG. 2B is a schematic cross section view of another embodiment ofintegrated driver LED package according to the present invention.

FIG. 3 is a schematic diagram of a pin-out configuration according toone embodiment of the invention containing an LED with integrateddriver.

FIG. 4 is a schematic diagram of one embodiment of the invention havingstep down converter and a current source drivers integrated with an LED.

FIG. 5 is a sectional view of one embodiment of an LED package accordingto the present invention.

FIG. 6 is a sectional view of another embodiment of and LED packageaccording to the present invention.

FIG. 7 is a sectional view of still another embodiment of an LED packageaccording to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In general, the present invention describes an LED package containingintegrated circuitry. In particular, the invention describes an LEDpackage containing integrated circuitry for matching a power sourcevoltage to the LED operating voltage, LEDs containing such integratedcircuitry, systems containing such packages, methods for matching thesource and operating voltages in such packages, and systems forcontrolling the emission properties of the packaged LEDs. The integratedcircuitry typically contains a power converter and a constant currentcircuit. In other embodiments the package may also contain other activeor passive components such as pin outs for internal or externalcomponents, a transformer and rectifier, or a rectifier circuit.Integrating the power supply and current control components into the LEDpackage can provide for fabrication of smaller LEDs packages thatrequire fewer and less device-specific components.

Other features and advantages of the invention will be apparent from thefollowing detailed description when taken together with the drawings,and from the claims. The following description presents preferredembodiments of the invention representing the best mode contemplated forpracticing the invention. This description is not to be taken in alimiting sense but is made merely for the purpose of describing thegeneral principles of the invention whose scope is defined by theappended claims.

Before addressing details of embodiments described below, some terms aredefined or clarified. As used herein, the terms “comprises,”“comprising,” “includes,” “including,” “has,” “having” or any othervariation thereof, are intended to cover a non-exclusive inclusion. Forexample, a process, method, article, or apparatus that comprises a listof elements is not necessarily limited to only those elements but mayinclude other elements not expressly listed or inherent to such process,method, article, or apparatus. Further, unless expressly stated to thecontrary, “or” refers to an inclusive or and not to an exclusive or. Forexample, a condition A or B is satisfied by any one of the following: Ais true (or present) and B is false (or not present), A is false (or notpresent) and B is true (or present), and both A and B are true (orpresent).

Also, use of the “a” or “an” are employed to describe elements andcomponents of the invention. This is done merely for convenience and togive a general sense of the invention. This description should be readto include one or at least one and the singular also includes the pluralunless it is obvious that it is meant otherwise.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Definitions used herein referto the particular embodiments described and are not to be taken aslimiting; the invention includes equivalents for other undescribedembodiments. Although methods and materials similar or equivalent tothose described herein can be used in the practice or testing of thepresent invention, suitable methods and materials are described below.In addition, the materials, methods, and examples are illustrative onlyand not intended to be limiting.

Attention is now directed to more specific details of embodiments thatillustrate but not limit the invention.

The present invention provides an LED package in which one or moresmaller active and passive components of constant-current power suppliesare integrated within the same package as the LED. Preferably, all theactive components of the power supply, as well as those passivecomponents which can be miniaturized, are integrated into the LEDpackage such that only the bulky passive components remain external tothe LED. It is understood, however, that as these bulky components arefurther miniaturized through technological advances, these componentscan also be integrated with an LED in the same package pursuant to thepresent invention.

One embodiment of an integrated LED package 10 according to the presentinvention is illustrated in block diagram form in FIG. 1, as containingthree functional blocks: a voltage converter 12, a constant currentcircuit 14, and an LED die/chip (“LED”) 16. The arrows in this diagramillustrate the direction in which the current may flow within thesethree blocks. This integrated LED configuration eliminates the need toinclude or design a separate voltage converter or current controlcircuit for each LED installation or application, making installationand use of LEDs much easier for the end user. The bulkier componentsnecessary for voltage conversion and constant current circuits could beincluded in functional blocks 12 or 14 in FIG. 1 or on other embodimentscould be included in separate functional blocks.

The components of the voltage converter and constant current circuit canbe arranged in many different ways within the LED packages according tothe present invention. These components can be formed on the samesemiconductor substrate as the LED or can be formed on one or moreseparate power semiconductor die or substrate (“power substrate”). Thepower substrate can then be integrated into the same electronic packagewith one or more LEDs. The power substrate and LED can be arranged inmany different ways such as in a vertical (e.g. stacked die) orhorizontal arrangement.

FIG. 2A illustrates one embodiment of a stacked LED package 20 accordingto the present invention containing a submount 22, power substrate 24,and LED 26. The power substrate 24 is mounted on the submount 22 and theLED 26 is mounted on the power substrate 24, both using known mountingmethods. The resulting structure has the power substrate 24 sandwichedbetween the submount 22 and the LED 26, with wire bonds 28 between thecomponents to provide the appropriate electrical interconnects and toconducted electrical signals between the components.

FIG. 2B illustrates another embodiment of an package 30 according to thepresent invention containing similar components to those in the stackedpackage 20. For similar components the same reference numeral is usedherein. The package 30 contains a submount 22, power substrate 24, LED26 and wire bonds 28. In this embodiment, however, the power substrate24 and LED 26 are horizontally arranged on the submount 22. That is, theLED 26 is mounted to the submount 22 adjacent to the power substrate 24.It is understood that these components can also be mounted in many otherways according to the present invention.

The voltage conversion and constant current circuits can be fabricatedon the power substrate using known semiconductor fabrication processesthat are not discussed in detail herein. The circuits can be formed fromknown semiconductor material systems on substrate made of knownmaterials.

The present invention is described herein with reference to LEDs, but itis understood that the present invention is also applicable to laserdiodes or other semiconductor devices which includes one or moresemiconductor layers. The fabrication and operation of LEDs is generallyknown in the art and only briefly discussed herein. The layers of an LEDcan be fabricated using known processes with a suitable process beingfabrication using metal organic chemical vapor deposition (MOCVD). Thelayers of LEDs generally comprise an active layer/region sandwichedbetween first and second oppositely doped epitaxial layers, all of whichare formed successively on a growth substrate. It is understood thatadditional layers and elements can also be included in an LED, includingbut not limited to buffer, nucleation, contact and current spreadinglayers as well as light extraction layers and elements. The activeregion can comprise single quantum well (SQW), multiple quantum well(MQW), double heterostructure or super lattice structures

The layers of the LED 26 may be fabricated from different materialsystems, with preferred material systems being Group-III nitride basedmaterial systems. Group-III nitrides refer to those semiconductorcompounds formed between nitrogen and the elements in the Group III ofthe periodic table, usually aluminum (Al), gallium (Ga), and indium(In). The term also refers to ternary and quaternary compounds such asaluminum gallium nitride (AlGaN) and aluminum indium gallium nitride(AlInGaN). In a preferred embodiment, the oppositely doped epitaxiallayers comprise gallium nitride (GaN) and the active region comprisesInGaN. In alternative embodiments the oppositely doped layers may beAlGaN, aluminum gallium arsenide (AlGaAs) or aluminum gallium indiumarsenide phosphide (AlGaInAsP).

The growth substrate can be made of many materials such as sapphire,silicon carbide, aluminum nitride (AlN), GaN, with a suitable substratebeing a 4H polytype of silicon carbide, although other silicon carbidepolytypes can also be used including 3C, 6H and 15R polytypes. Siliconcarbide has certain advantages, such as a closer crystal lattice matchto Group III nitrides than sapphire and results in Group III nitridefilms of higher quality. Silicon carbide also has a very high thermalconductivity so that the total output power of Group-III nitride deviceson silicon carbide is not limited by the thermal dissipation of thesubstrate (as may be the case with some devices formed on sapphire). SiCsubstrates are available from Cree Research, Inc., of Durham, N.C. andmethods for producing them are set forth in the scientific literature aswell as in a U.S. Pat. Nos. Re. 34,861; 4,946,547; and 5,200,022.

It is further understood that the LED 26 can also be coated by a downconversion material that is preferably a phosphor. The phosphor coatingcan be applied using different processes such as spin coating,electrophoretic deposition, electrostatic deposition, printing, jetprinting or screen printing. Many different phosphors can be used tocoat the LED according to the present invention. The present inventionis particularly adapted to LED packages emitting white light. In oneembodiment according to the present invention the LED 26 can emit lightin the blue wavelength spectrum from its active region and the phosphorabsorbs some of the blue light and re-emits yellow. The LED 26 emits awhite light combination of blue and yellow light. In one embodiment thephosphor comprises commercially available YAG:Ce, although a full rangeof broad yellow spectral emission is possible using conversion particlesmade of phosphors based on the (Gd,Y)₃(Al,Ga)₅O₁₂:Ce system, such as theY₃Al₅O₁₂:Ce (YAG). It is understood however, that other yellow phosphorscan also be used and that other phosphors or materials can be used forthe coating.

The submount 22 may be formed of many different materials with apreferred material being electrically insulating. Suitable substratematerial include, but are not limited to ceramic materials such asaluminum-oxide or aluminum-nitride. The submount 22 can also compriseelectrical traces and an LED mounting pad, with LED 26 mounted to themounting pad and the electrical traces providing a conductive path forelectrical connection to the LED 26. The electrical traces provideelectrical connection to the LED 26 either directly to the LED (withoutwire bonds) or by one or more bond wires between one of the traces andthe LED.

As mentioned above, driving LEDs can also require large passiveelectrical components (e.g., inductors, transformers, capacitors) forvoltage conversion or constant current supplies. In other embodimentswhere the primary power source is alternating current (AC) separate ACto DC conversion devices may also be needed such a transformer orrectifier circuits. In some embodiments all or a portion of thesecircuits can be integrated in the LED package, while in others the sizeof these components can be larger than the LED packages themselves. Inthese embodiments, pin-outs can be included as part of the LED packagewhich allow the external connection to these larger external componentsusing known interconnection schemes, such as through conductive tracesof a printed circuit board. The pin-outs can be configured in manydifferent ways with FIG. 3 showing one embodiment of an LED package 30according to the present invention having a pin-out configuration for anLED package with integrated voltage converter and constant currentcircuits. The C+ 31, C− 32, L+ 34, and L− 35 pins can be used for therequired passive components, and additional pin-outs may be necessary toset the LED current and to allow for dimming control. A normal LED, bycomparison, would have only anode Vin+ 37 and cathode Vin− 38connections.

In different embodiments according to the present invention, the choiceof voltage converter components and interconnection depends on whetherthe input voltage that is to be converted is greater than, less than, orvaries from greater than to less than the voltage necessary to drive theLEDs at the desired operating current. Non-limiting examples ofconverters suitable for use with the invention include a step-down(buck) converter used when the input voltage is greater than the LEDvoltage, a step-up (boost) converter used when the input voltage is lessthan the LED voltage, a buck-boost converter used in situations wherethe input voltage can vary from above to below the LED voltage (e.g.when the battery supplying the input voltage starts at a voltage abovethe LED voltage but decreases with usage to below the LED voltage), aswell as a flying capacitor or charge-pump, linear voltage regulator.These circuits a generally known in the art and one example of thesecircuits is shown in FIG. 4 and discussed below.

The constant current circuit of the present invention may be asrudimentary as a current-limiting resistor in series with the LED die,although this may not be the most efficient method of producing aconstant current. Other types of constant current circuits suitable forthe invention include without limitation JFET current sources and linearregulators with current sensing and feedback using operationalamplifiers, all of which are generally known in the art.

FIG. 4 is a schematic diagram of one embodiment LED package 40 accordingto the present invention which comprises voltage converter 41 thatincludes a step down converter 42 and external passive components 48.The package 40 further comprises a constant current source circuit 44and an LED 46. In the embodiment shown, the converter 42, LED 46 andcircuit 44 are integrated in the LED package 40 as described above. Theexternal passive external components 48 are not integrated in the LEDpackage 40, but can be coupled to the LED package 40 to complete thevoltage converter 41, such as through the pin-outs described above andshown in FIG. 3. As mentioned above, the bulky passive components, suchas transformers, can be integrated onto the LED package 40 as they arefurther miniaturized through technological advances.

As described above, many different voltage converters can be used in thepresent invention, with the voltage converter 42 comprising a step down(buck) voltage converter. Many different components can be used for thevoltage converter 42, with the voltage converter 42 as shown comprisinga transistor 50, oscillator 52 and a diode 54 interconnected as shown.The external components 48 can also comprise many different components,with the embodiment shown comprising a inductor 56 and a capacitor 58.Step down operation of the voltage converter 42 is generally known inthe art and only briefly discussed herein. The step down operation ofthe voltage converter 42 generally results from cooperation of theinductor 56 on the external components 48 with the operation of thetransistor 50 and the diode 54. The oscillator 52 controls when thetransistor 50 is in on-state, and when in the on-state a voltage V_(L)is applied to the inductor 50 as V_(L)=V_(i)−V_(o). During this on-statecurrent through the inductor 50 rises linearly, and the diode 54 isreverse biased by the input voltage so that no current flows through it.When the transistor 50 is brought to an off-state by the oscillator 52,the diode 54 is forward biased and voltage V_(L) at the inductor 50 isV_(L)=−V_(o) (neglecting diode voltage drop). Accordingly, the currentthrough the inductor decreases. From this operation, the output voltageV_(o) varies linearly with the duty cycle of the input voltage V_(i),which is controlled by the duty cycle of the oscillator 52. So, forexample, stepping down an output voltage so that it is equal to a fourthof the input voltage would require a oscillator with a duty cycle ofapproximately 25%.

The constant current circuit 44 is coupled to the LED as shown andmaintains a relatively constant current flowing through the LED 46. Manydifferent constant current circuits can be used according to the presentinvention, with the circuit 44 as shown comprising a junction fieldeffect transistor (JFET) 60. As is generally known in the art, a JFETcan be made to act as a current source by tying its gate to its sourceas shown. The current then flowing is the I_(DSS) of the JFET. Asdiscussed above, in different embodiments different voltage converterand constant current circuits can be used, such as a knownboost-converter, which can also require an external inductor andcapacitor to increase the voltage from the input side to a higher level,in order to drive the LED and current source. In other embodiments theJFET could be replaced by a current sensing resistor as well as adetection and feedback circuit to control the duty cycle of theoscillator such that the supply current to the LED is constant.

The present invention can be used in many different package types, withone embodiment of an LED package 70 shown in FIG. 5. The package 70contains a submount 72, power substrate 74, LED 76 and wire bonds 78,similar to those shown in FIG. 2 b and described above. The package 70,further comprises a reflective cup 80 arranged to reflect lightgenerated by the LED 80 so that the reflected light can contribute touseful light emission from the package 70. The reflective cup can bemade of a material that reflects/scatters light from the LED 76. Manydifferent materials can be used, such as high melting temperaturematerials including plastics.

The package 70 also comprises an encapsulant 82 that fills the areawithin the reflective cup 80, covering the surface of the subount 72, aswell as the power substrate 74, LED 76 and wire bonds 78. Many differentmaterials can be used for the encapsulant including but not limited tosilicones or polymers. A lens 84 is included on the encapsulant 82, withthe encapsulation material preferably being a high temperature polymerwith high light transmissivity and a refractive index that matches orclosely matches the refractive index of the lens 84. The lens can bemade of many different light transmitting materials such as glass,quartz, high temperature and transparent plastic, silicone or acombination of these materials. The lens 84 is preferably placed on topof and adheres to the encapsulant 82. This arrangement provides for anLED package 70 that is robust and integrates many of the electroniccomponents necessary for efficient operation.

FIG. 6 shows another embodiment of an LED package 90 according to thepresent invention having a LED 76, wire bond 78, reflective cup 80,encapsulant 82 and lens 84 similar to those in LED package 70 describedabove. This embodiment also comprises a submount 92, but instead of aseparate power substrate the voltage converter and constant currentcircuit components are fabricated as part of the submount 92 is adeposition region 94. The circuit components can be fabricated usingknown semiconductor fabrication processes and the submount 92 can bemade of many different materials compatible with the formation ofsemiconductor materials. The deposition region 94 is shown at the bottomof the submount 92 although it can be located in different areas. Thesubmount 92 can also comprise conductive vias 96 to transmit electricalsignals from the deposition region 94 to the LED 76. By having thevoltage conversion and constant current circuit elements on the submount92 opposite the LED 76 can reduce heat build-up during packageoperation.

FIG. 7 shows another embodiment of an LED package 100 according to alsohaving a LED 76, wire bond 78, reflective cup 80, encapsulant 82 andlens 84 similar to those in LED package 70 described above. Thisembodiment also comprises a submount 102 having a deposition region 104where the voltage converter and constant current circuit elements aredeposited. In this embodiment, however, the deposition region is on thesame surface of the submount 104 as the LED 76. The LED 76 can bemounted directly on and in electrical contact with the deposition region104 as shown, or in other embodiments can be adjacent to it.

The present invention can be used to fabricate a number of differentdevice types, including without limitation photoelectronic, electronic,and semiconductor devices. The arrangement or configuration ofcomponents of packages according to the present invention may bedesigned to minimize the effects of heat generated by the powersubstrate or deposition regions, and LED. Non limiting examples ofconfigurations which facilitate heat dissipation include using chipcomponents having high thermal conductivity and as mentioned aboveplacing the power substrate or deposition region at the bottom of apackage. Although these arrangements can require vias to connectelectrical signals, they typically have better heat dissipation thanother types of device packages because the circuitry is separated fromthe LED.

It is understood that although the present invention has been describedherein with reference to a single power substrate or deposition regionused in combination with an LED, multiple power substrates or depositionregions can also be used. It is further understood that each of the LEDpackages described herein can be used with other emitter or multipleLEDs emitting the same or different colors/wavelengths of light (e.g. inorder to emit red, green, and blue light). This may require differentfunctional components or current levels for the LEDs.

The embodiments and examples set forth herein were presented to explainthe nature of the present invention and its practical application, andthereby to enable those of ordinary skill in the art to make and use theinvention. However, those of ordinary skill in the art will recognizethat the foregoing description and examples have been presented for thepurposes of illustration and example only. The description as set forthis not intended to be exhaustive or to limit the invention to theprecise form disclosed. Many modifications and variations are possiblein light of the teachings above without departing from the spirit andscope of the forthcoming claims. One skilled in the art will recognizethat the invention may potentially be applied to many types of lightingsystems.

1. A light emitting device package comprising: at least one LED havingat least one operating voltage; and circuitry comprising at least onevoltage level converter and at least one constant current circuit,wherein the at least one converter and the at least one circuit areintegrated into the package and electrically connected to the LED,further comprising at least one first electrical connector, wherein theat least one first connector provides an electrical connection to atleast one control system, wherein the at least one control system isconnected to the package though at least one of a serial bus, a parallelbus, and combinations thereof.
 2. The package of claim 1, wherein thecircuitry comprises drive circuitry.
 3. The package of claim 1, whereinthe circuitry provides the at least one operating voltage to the LED. 4.The package of claim 1, wherein the at least one voltage converter isselected from the group consisting of a DC voltage converter, a chargepump, a switched-mode power supply, and combinations thereof.
 5. Thepackage of claim 1, further comprising at least one transformer and atleast one rectifier.
 6. The package of claim 1, wherein the at least onefirst connector further provides an electrical connection to at leastone power source.
 7. The package of claim 1, wherein the at least onecontrol system provides control over at least one LED current.
 8. Thepackage of claim 1, wherein the at least one control system providescontrol over at least one property of light emitted by the LED.
 9. Apackaged LED comprising the device package of claim
 1. 10. A lightemitting system comprising the package of claim
 1. 11. The system ofclaim 10, further comprising at least one power source.
 12. The systemof claim 10, further comprising at least one control system.
 13. Thesystem of claim 12, wherein the control system is connected to thepackage and provides control over at least one property of light emittedby the LED.
 14. A light emitting device package comprising: at least oneLED having at least one operating voltage; and circuitry comprising atleast one voltage level converter and at least one constant currentcircuit, wherein the at least one converter and the at least one circuitare integrated into the package and electrically connected to the LED,further comprising at least one control system, wherein the controlsystem is connected to the package and provides control over at leastone property of light emitted by the LED, and wherein the at least onecontrol system is connected to the package through at least one of aserial bus, a parallel bus, and combinations thereof.
 15. The package ofclaim 14, wherein the circuitry comprises drive circuitry.
 16. Thepackage of claim 14, further comprising at least one transformer and atleast one rectifier.
 17. The package of claim 14, further providing anelectrical connection to at least one power source.
 18. The package ofclaim 14, wherein the at least one control system provides control overat least one LED current.
 19. The package of claim 14, wherein the atleast one control system provides control over at least one property oflight emitted by the LED.
 20. A packaged LED comprising the devicepackage of claim
 15. 21. A light emitting system comprising the packageof claim 15.